Re: System event sounds / audio feedback

[Lennart Poettering <mztabzr 0pointer de>]

On Wed, 21.11.07 20:47, Stéphan Kochen (stephan kochen nl) wrote:

> 1) A replacement for the libgnome could be a GTK+ module, that simply
> hooks signals and plays sounds. Sounds are preloaded by settings-daemon;
> no difference from the current situation there.
> 
> The GTK+ module can use PulseAudio's GLib mainloop integration. Playing
> sounds from the sample cache is asynchronous.

This is more or less what I plan to do with "libcanberra" (which is
still vaporware right now, though). As described in huge email about
PA which I wrote on d-d-l:

http://mail.gnome.org/archives/desktop-devel-list/2007-October/msg00136.html

(Look for the part "So, where do we go from here?")

> 2) More events becomes a problem when thinking beyond just the fixed set
> for a GUI toolkit; about feedback from application specific functions.
> Opening a folder and browsing to a page are good examples of this.
> 
> A possible solution would be to dedicate a GConf directory for sound
> events. Control-center iterates directory entries to find configurable
> sounds and their descriptions. (Short description in the listview, long
> in the tooltip for example.) Applications namespace their event names to
> avoid conflicts.
> 
> 3) Theming is a matter of defining a format and implementing the
> configuration for it. This could be a dead simple archive containing
> wave or Ogg Vorbis files named after the GConf event names they play
> for.

The problem with themeing and adding more sound events is that there
are no better sounds available then what we have right now. I have
never seen any free samples that are even remotely as useful as the
current gnome-audio samples, and I am not even speaking of the quality
the the MacOSX sounds have. And quite frankly, the gnome-audio samples
are still annoying.

So, making this stuff themeable, and adding a wealth of additional event
sources, is kind of pointless if we don't have any good event sounds
to actually play.

The "Bango" project (http://www.freedesktop.org/wiki/Bango) tried to
come up with a themeing spec and better sounds. But AFAIK it never
yielded any useful results.

With libcanberra I will make it easier to add sound event hooks to
applications. However, if someone really wants to see the sound
theming happen, then he probably should start with coming up with
better event sounds, first. 

I mean, we have been shipping these audio samples for 10 years or so
now -- and AFAIK noone ever contributed any new sounds.

> 4) This is slightly tricky. A volume can be specified when playing the
> sample. Along the lines of the previous solutions, this means the GTK+
> module needs to access the configuration somehow to get the volume. I'm
> not sure if a GConf dependency in a generic GTK+ module is a good idea.
> 
> PulseAudio also stores a default volume for samples in the cache, but
> there's nothing in the documentation on how to set this. Perhaps this is
> some extra work that needs to be done on the PulseAudio side.

Adjusting the volume or the devices event sounds are played on is
currently not possible in PA without making your hands dirty by editing
configuration files. In one of the next versions I will add a flexible
meta information and matching system to PA, which will allow writing volume
controls that allow you to change volumes of certain subsets of audio
streams at a whole. I.e. think of the current pavucontrol but with an
extra track for "Event Sounds". (Similar to what Vista does)

Lennart

-- 
Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net         ICQ# 11060553
http://0pointer.net/lennart/           GnuPG 0x1A015CC4